Certify? What, like sign a statement, similar to the 'pledge of allegiance' that Republican & independent voters in Ohio had to sign in order to vote on a Democrat ballot, and are now being threatened with legal actions and fines for making false statements?
Surely there is a law in Michigan that says you can’t vote twice in a single election - not just testifying that you didn’t should not be good enough. Any old lawyer should be able to tie this thing up in court long enough to make the whole issue moot.